1 /* Run-time dynamic linker data structures for loaded ELF shared objects.
2 Copyright (C) 1995-1999, 2000 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Library General Public License as
7 published by the Free Software Foundation; either version 2 of the
8 License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Library General Public License for more details.
15 You should have received a copy of the GNU Library General Public
16 License along with the GNU C Library; see the file COPYING.LIB. If not,
17 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
18 Boston, MA 02111-1307, USA. */
36 /* We use this macro to refer to ELF types independent of the native wordsize.
37 `ElfW(TYPE)' is used in place of `Elf32_TYPE' or `Elf64_TYPE'. */
38 #define ELFW(type) _ElfW (ELF, __ELF_NATIVE_CLASS, type)
40 /* All references to the value of l_info[DT_PLTGOT],
41 l_info[DT_STRTAB], l_info[DT_SYMTAB], l_info[DT_RELA],
42 l_info[DT_REL], l_info[DT_JMPREL], and l_info[VERSYMIDX (DT_VERSYM)]
43 have to be accessed via the D_PTR macro. The macro is needed since for
44 most architectures the entry is already relocated - but for some not
45 and we need to relocate at access time. */
46 #ifdef DL_RO_DYN_SECTION
47 # define D_PTR(map,i) (map->i->d_un.d_ptr + map->l_addr)
49 # define D_PTR(map,i) map->i->d_un.d_ptr
52 /* For the version handling we need an array with only names and their
54 struct r_found_version
63 /* We want to cache information about the searches for shared objects. */
65 enum r_dir_status { unknown, nonexisting, existing };
67 struct r_search_path_elem
69 /* This link is only used in the `all_dirs' member of `r_search_path'. */
70 struct r_search_path_elem *next;
72 /* Strings saying where the definition came from. */
76 /* Basename for this search path element. The string must end with
81 enum r_dir_status status[0];
91 /* A data structure for a simple single linked list of strings. */
94 const char *name; /* Name requested (before search). */
95 struct libname_list *next; /* Link to next name for this object. */
99 /* Test whether given NAME matches any of the names of the given object. */
101 __attribute__ ((unused))
102 _dl_name_match_p (const char *__name, struct link_map *__map)
104 int __found = strcmp (__name, __map->l_name) == 0;
105 struct libname_list *__runp = __map->l_libname;
107 while (! __found && __runp != NULL)
108 if (strcmp (__name, __runp->name) == 0)
111 __runp = __runp->next;
116 /* Function used as argument for `_dl_receive_error' function. The
117 arguments are the error code, error string, and the objname the
118 error occurred in. */
119 typedef void (*receiver_fct) (int, const char *, const char *);
121 /* Internal functions of the run-time dynamic linker.
122 These can be accessed if you link again the dynamic linker
123 as a shared library, as in `-lld' or `/lib/ld.so' explicitly;
124 but are not normally of interest to user programs.
126 The `-ldl' library functions in <dlfcn.h> provide a simple
127 user interface to run-time dynamic linking. */
130 /* Parameters passed to the dynamic linker. */
131 extern char **_dl_argv;
133 /* Cached value of `getpagesize ()'. */
134 extern size_t _dl_pagesize;
136 /* File descriptor referring to the zero-fill device. */
137 extern int _dl_zerofd;
139 /* Name of the shared object to be profiled (if any). */
140 extern const char *_dl_profile;
141 /* Map of shared object to be profiled. */
142 extern struct link_map *_dl_profile_map;
143 /* Filename of the output file. */
144 extern const char *_dl_profile_output;
146 /* If nonzero the appropriate debug information is printed. */
147 extern int _dl_debug_libs;
148 extern int _dl_debug_impcalls;
149 extern int _dl_debug_bindings;
150 extern int _dl_debug_symbols;
151 extern int _dl_debug_versions;
152 extern int _dl_debug_reloc;
153 extern int _dl_debug_files;
155 /* Expect cache ID. */
156 extern int _dl_correct_cache_id;
158 /* Mask for hardware capabilities that are available. */
159 extern unsigned long int _dl_hwcap;
161 /* Mask for important hardware capabilities we honour. */
162 extern unsigned long int _dl_hwcap_mask;
164 /* File descriptor to write debug messages to. */
165 extern int _dl_debug_fd;
167 /* Names of shared object for which the RPATH should be ignored. */
168 extern const char *_dl_inhibit_rpath;
170 /* OS-dependent function to open the zero-fill device. */
171 extern int _dl_sysdep_open_zero_fill (void); /* dl-sysdep.c */
173 /* OS-dependent function to write a message on the specified
174 descriptor FD. All arguments are `const char *'; args until a null
175 pointer are concatenated to form the message to print. */
176 extern void _dl_sysdep_output (int fd, const char *string, ...);
178 /* OS-dependent function to write a debug message on the specified
179 descriptor for this. All arguments are `const char *'; args until
180 a null pointer are concatenated to form the message to print. If
181 NEW_LINE is nonzero it is assumed that the message starts on a new
183 extern void _dl_debug_message (int new_line, const char *string, ...);
185 /* OS-dependent function to write a message on the standard output.
186 All arguments are `const char *'; args until a null pointer
187 are concatenated to form the message to print. */
188 #define _dl_sysdep_message(string, args...) \
189 _dl_sysdep_output (STDOUT_FILENO, string, ##args)
191 /* OS-dependent function to write a message on the standard error.
192 All arguments are `const char *'; args until a null pointer
193 are concatenated to form the message to print. */
194 #define _dl_sysdep_error(string, args...) \
195 _dl_sysdep_output (STDERR_FILENO, string, ##args)
197 /* OS-dependent function to give a fatal error message and exit
198 when the dynamic linker fails before the program is fully linked.
199 All arguments are `const char *'; args until a null pointer
200 are concatenated to form the message to print. */
201 #define _dl_sysdep_fatal(string, args...) \
204 _dl_sysdep_output (STDERR_FILENO, string, ##args); \
209 /* Nonzero if the program should be "secure" (i.e. it's setuid or somesuch).
210 This tells the dynamic linker to ignore environment variables. */
211 extern int _dl_secure;
213 /* This function is called by all the internal dynamic linker functions
214 when they encounter an error. ERRCODE is either an `errno' code or
215 zero; OBJECT is the name of the problematical shared object, or null if
216 it is a general problem; ERRSTRING is a string describing the specific
218 extern void _dl_signal_error (int errcode,
220 const char *errstring)
222 __attribute__ ((__noreturn__));
224 /* Like _dl_signal_error, but may return when called in the context of
225 _dl_receive_error. */
226 extern void _dl_signal_cerror (int errcode,
228 const char *errstring)
231 /* Call OPERATE, receiving errors from `dl_signal_cerror'. Unlike
232 `_dl_catch_error' the operation is resumed after the OPERATE
234 ARGS is passed as argument to OPERATE. */
235 extern void _dl_receive_error (receiver_fct fct, void (*operate) (void *),
240 /* Open the shared object NAME and map in its segments.
241 LOADER's DT_RPATH is used in searching for NAME.
242 If the object is already opened, returns its existing map.
243 For preloaded shared objects PRELOADED is set to a non-zero
244 value to allow additional security checks. */
245 extern struct link_map *_dl_map_object (struct link_map *loader,
246 const char *name, int preloaded,
247 int type, int trace_mode)
250 /* Call _dl_map_object on the dependencies of MAP, and set up
251 MAP->l_searchlist. PRELOADS points to a vector of NPRELOADS previously
252 loaded objects that will be inserted into MAP->l_searchlist after MAP
253 but before its dependencies. */
254 extern void _dl_map_object_deps (struct link_map *map,
255 struct link_map **preloads,
256 unsigned int npreloads, int trace_mode)
259 /* Cache the locations of MAP's hash table. */
260 extern void _dl_setup_hash (struct link_map *map) internal_function;
263 /* Search loaded objects' symbol tables for a definition of the symbol
264 referred to by UNDEF. *SYM is the symbol table entry containing the
265 reference; it is replaced with the defining symbol, and the base load
266 address of the defining object is returned. SYMBOL_SCOPE is a
267 null-terminated list of object scopes to search; each object's
268 l_searchlist (i.e. the segment of the dependency tree starting at that
269 object) is searched in turn. REFERENCE_NAME should name the object
270 containing the reference; it is used in error messages.
271 RELOC_TYPE is a machine-dependent reloc type, which is passed to
272 the `elf_machine_lookup_*_p' macros in dl-machine.h to affect which
273 symbols can be chosen. */
274 extern ElfW(Addr) _dl_lookup_symbol (const char *undef,
275 struct link_map *undef_map,
276 const ElfW(Sym) **sym,
277 struct r_scope_elem *symbol_scope[],
281 /* Lookup versioned symbol. */
282 extern ElfW(Addr) _dl_lookup_versioned_symbol (const char *undef,
283 struct link_map *undef_map,
284 const ElfW(Sym) **sym,
285 struct r_scope_elem *symbol_scope[],
286 const struct r_found_version *version,
290 /* For handling RTLD_NEXT we must be able to skip shared objects. */
291 extern ElfW(Addr) _dl_lookup_symbol_skip (const char *undef,
292 struct link_map *undef_map,
293 const ElfW(Sym) **sym,
294 struct r_scope_elem *symbol_scope[],
295 struct link_map *skip_this)
298 /* For handling RTLD_NEXT with versioned symbols we must be able to
299 skip shared objects. */
300 extern ElfW(Addr) _dl_lookup_versioned_symbol_skip (const char *undef,
301 struct link_map *undef_map,
302 const ElfW(Sym) **sym,
303 struct r_scope_elem *symbol_scope[],
304 const struct r_found_version *version,
305 struct link_map *skip_this)
308 /* Look up symbol NAME in MAP's scope and return its run-time address. */
309 extern ElfW(Addr) _dl_symbol_value (struct link_map *map, const char *name)
313 /* Structure describing the dynamic linker itself. */
314 extern struct link_map _dl_rtld_map;
315 /* And a pointer to the map for the main map. */
316 extern struct link_map *_dl_loaded;
317 /* Array representing global scope. */
318 extern struct r_scope_elem *_dl_global_scope[2];
319 /* Direct pointer to the searchlist of the main object. */
320 extern struct r_scope_elem *_dl_main_searchlist;
321 /* Copy of the content of `_dl_main_searchlist'. */
322 extern struct r_scope_elem _dl_initial_searchlist;
323 /* This is zero at program start to signal that the global scope map is
324 allocated by rtld. Later it keeps the size of the map. It might be
325 reset if in _dl_close if the last global object is removed. */
326 extern size_t _dl_global_scope_alloc;
328 /* Allocate a `struct link_map' for a new object being loaded,
329 and enter it into the _dl_main_map list. */
330 extern struct link_map *_dl_new_object (char *realname, const char *libname,
331 int type, struct link_map *loader)
334 /* Relocate the given object (if it hasn't already been).
335 SCOPE is passed to _dl_lookup_symbol in symbol lookups.
336 If LAZY is nonzero, don't relocate its PLT. */
337 extern void _dl_relocate_object (struct link_map *map,
338 struct r_scope_elem *scope[],
339 int lazy, int consider_profiling);
341 /* Call _dl_signal_error with a message about an unhandled reloc type.
342 TYPE is the result of ELFW(R_TYPE) (r_info), i.e. an R_<CPU>_* value.
343 PLT is nonzero if this was a PLT reloc; it just affects the message. */
344 extern void _dl_reloc_bad_type (struct link_map *map,
345 uint_fast8_t type, int plt)
348 /* Check the version dependencies of all objects available through
349 MAP. If VERBOSE print some more diagnostics. */
350 extern int _dl_check_all_versions (struct link_map *map, int verbose,
354 /* Check the version dependencies for MAP. If VERBOSE print some more
356 extern int _dl_check_map_versions (struct link_map *map, int verbose,
360 /* Initialize the object in SCOPE by calling the constructors with
361 ARGC, ARGV, and ENV as the parameters. */
362 extern void _dl_init (struct link_map *main_map, int argc, char **argv,
363 char **env) internal_function;
365 /* Call the finalizer functions of all shared objects whose
366 initializer functions have completed. */
367 extern void _dl_fini (void) internal_function;
369 /* The dynamic linker calls this function before and having changing
370 any shared object mappings. The `r_state' member of `struct r_debug'
371 says what change is taking place. This function's address is
372 the value of the `r_brk' member. */
373 extern void _dl_debug_state (void);
375 /* Initialize `struct r_debug' if it has not already been done. The
376 argument is the run-time load address of the dynamic linker, to be put
377 in the `r_ldbase' member. Returns the address of the structure. */
378 extern struct r_debug *_dl_debug_initialize (ElfW(Addr) ldbase)
381 /* Initialize the basic data structure for the search paths. */
382 extern void _dl_init_paths (const char *library_path) internal_function;
384 /* Gather the information needed to install the profiling tables and start
386 extern void _dl_start_profile (struct link_map *map, const char *output_dir)
389 /* The actual functions used to keep book on the calls. */
390 extern void _dl_mcount (ElfW(Addr) frompc, ElfW(Addr) selfpc);
392 /* This function is simply a wrapper around the _dl_mcount function
393 which does not require a FROMPC parameter since this is the
395 extern void _dl_mcount_wrapper (void *selfpc);
397 /* Show the members of the auxiliary array passed up from the kernel. */
398 extern void _dl_show_auxv (void) internal_function;
400 /* Return all environment variables starting with `LD_', one after the
402 extern char *_dl_next_ld_env_entry (char ***position) internal_function;
404 /* Return an array with the names of the important hardware capabilities. */
405 extern const struct r_strlenpair *_dl_important_hwcaps (const char *platform,
408 size_t *max_capstrlen)
413 #endif /* ldsodefs.h */